Characteristics of tuberculosis source cases identified

(HealthDay)—In 26 U.S. tuberculosis outbreaks the initial source case-patients had long incubation periods and were characterized by substance abuse, incarceration, and homelessness, according to a study published in the March issue of the U.S. Centers for Disease Control and Prevention's Emerging Infectious Disease.

Maryam B. Haddad, M.P.H., from the CDC in Atlanta, and colleagues reviewed the characteristics of tuberculosis cases that started outbreaks in the United States during 2002 to 2011. They examined the initial source case for 26 tuberculosis outbreaks.

The researchers found that in 20 of the outbreaks the source case-patient was also the first patient in the outbreak to come to the attention of public health authorities. Case-patients had long infectious periods (median, 10 months); these patients often experienced delays in diagnosis and treatment initiation after seeking medical attention for tuberculosis symptoms. Pulmonary tuberculosis smear-positive for acid-fast bacilli was confirmed in all case patients. Most patients reported excess alcohol or illicit drug use; half had been incarcerated, and nearly half had been homeless in the year prior to diagnosis. Most of the cases came to public attention because the patient sought care for symptoms.

"This review underscores the particular importance of prompt and thorough investigations for tuberculosis cases confirmed by positive smear for acid-fast bacilli in which patients have experienced substance abuse, incarceration, or homelessness," the authors write.